Apparatus and method for generating broadcast signal frame using layered division multiplexing

ABSTRACT

An apparatus and method for generating broadcast signal frame using layered division multiplexing are disclosed. The apparatus includes a combiner configured to generate a multiplexed signal by combining a core layer signal and an enhanced layer signal at different power levels; a power normalizer configured to reduce the power of the multiplexed signal to a power level corresponding to the core layer signal; a time interleaver configured to generate a time-interleaved signal by performing interleaving that is applied to both the core layer signal and the enhanced layer signal; and a frame builder configured to generate a broadcast signal frame including a bootstrap and a preamble using the time-interleaved signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 17/746,799 filed May 17, 2022, which is a continuation of U.S.patent application Ser. No. 16/880,545 filed May 21, 2020 and now issuedas U.S. Pat. No. 11,368,955, which is a continuation of U.S. patentapplication Ser. No. 16/243,831 filed Jan. 9, 2019 and now issued asU.S. Pat. No. 10,701,689, which is a continuation of U.S. patentapplication Ser. No. 15/504,298 filed Feb. 15, 2017 and now issued asU.S. Pat. No. 10,225,835, which is a U.S. National Stage ofInternational Patent Application No. PCT/KR2015/008846 filed Aug. 25,2015, which claims priority to and the benefit of Korean PatentApplication Nos. 10-2014-0111090 and 10-2015-0118763 filed in the KoreanIntellectual Property Office on Aug. 25, 2014 and Aug. 24, 2015,respectively, the entire contents of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to broadcast signal transmission/receptiontechnology that is used in a broadcasting system and, more particularly,to a broadcast signal transmission/reception system thatmultiplexes/demultiplexes and then transmits/receives two or moresignals.

BACKGROUND ART

Bit-Interleaved Coded Modulation (BICM) is bandwidth-efficienttransmission technology, and is implemented in such a manner that anerror-correction coder, a bit-by-bit interleaver and a high-ordermodulator are combined with one another.

BICM can provide excellent performance using a simple structure becauseit uses a low-density parity check (LDPC) coder or a Turbo coder as theerror-correction coder. Furthermore, BICM can provide high-levelflexibility because it can select modulation order and the length andcode rate of an error correction code in various forms. Due to theseadvantages, BICM has been used in broadcasting standards, such as DVB-T2and DVB-NGH, and has a strong possibility of being used in othernext-generation broadcasting systems.

To support multiple services at the same time, multiplexing, i.e., theprocess of mixing a plurality of signals, is required. Of multiplexingtechniques, currently widely used techniques include Time DivisionMultiplexing (TDM) adapted to divide and use time resources andFrequency Division Multiplexing (FDM) adapted to divide and usefrequency resources. That is, TDM is a method of assigning time segmentsto respective services, and FDM is a technique for assigning frequencyresource segments to respective services and then using them. Recently,there is an urgent need for new multiplexing technology that isapplicable to a next generation broadcasting system and provides greaterflexibility and performance than TDM and FDM.

DISCLOSURE Technical Problem

An object of the present invention is to provide a broadcast signalframe structure in which new signal multiplexing technologies capable ofproviding greater flexibility and performance than TDM and FDM areapplied.

Furthermore, an object of the present invention is to enable eachservice to use 100% of time and frequency resources while supportingmultiple services in a next generation broadcasting system at the sametime.

Furthermore, an object of the present invention is to efficientlymultiplex/demultiplex signals corresponding to two or more layers bycombining the signals at respective different power levels.

Technical Solution

In order to accomplish the above objects, the present invention providesan apparatus for generating broadcast signal frame, including: acombiner configured to generate a multiplexed signal by combining a corelayer signal and an enhanced layer signal at different power levels; apower normalizer configured to reduce the power of the multiplexedsignal to a power level corresponding to the core layer signal; a timeinterleaver configured to generate a time-interleaved signal byperforming interleaving that is applied to both the core layer signaland the enhanced layer signal; and a frame builder configured togenerate a broadcast signal frame including a bootstrap and a preambleusing the time-interleaved signal.

In this case, the frame builder may include a bootstrap generatorconfigured to generate the bootstrap; a preamble generator configured togenerate the preamble; and a super-imposed payload generator configuredto generate a super-imposed payload corresponding to thetime-interleaved signal.

In this case, the bootstrap may be shorter than the preamble, and have afixed length.

In this case, the bootstrap may include a symbol representing astructure of the preamble, the symbol corresponding to a fixed-lengthbit string representing a combination of a modulation scheme/code rate,a FFT size, a guard interval length and a pilot pattern of the preamble.

In this case, the symbol may correspond to a lookup table in which apreamble structure corresponding to a second FFT size is allocated priorto a preamble structure corresponding to a first FFT size, the secondFFT size being less than the first FFT size when the modulationscheme/code rates are the same, and a preamble structure correspondingto a second guard interval length is allocated prior to a preamblestructure corresponding to a first guard interval length, the secondguard interval length being longer than the first guard interval lengthwhen the modulation scheme/code rates are the same and the FFT sizes arethe same.

In this case, the being allocated prior to other preamble structure maymean having a serial number less than the serial number of the otherpreamble structure in the lookup table.

In this case, the apparatus may further include an injection levelcontroller configured to generate a power-reduced enhanced layer signalby reducing the power of the enhanced layer signal. In this case, thecombiner may generate the multiplexed signal by combining the core layersignal and the power-reduced enhanced layer signal.

In this case, the apparatus may further include a signaling generationunit configured to generate signaling information including theinjection level information of the injection level controller.

In this case, the apparatus may further include: a core layerBit-Interleaved Coded Modulation (BICM) unit configured to correspond tothe core layer signal; and an enhanced layer BICM unit configured toperform Bit-Interleaved Coded Modulation (BICM) encoding different fromthat of the core layer BICM unit.

In this case, the core layer BICM unit may have a lower bit rate thanthe enhanced layer BICM unit, and may be more robust than the enhancedlayer BICM unit.

In this case, the power normalizer may correspond to a normalizingfactor, and may reduce the power of the multiplexed signal by a level bywhich the power has been increased by the combiner.

In this case, the injection level controller may correspond to a scalingfactor. In this case, each of the normalizing factor and the scalingfactor may be a value that is larger than 0 and smaller than 1, thescaling factor may decrease as a reduction in power corresponding to theinjection level controller becomes larger, and the normalizing factormay increase as a reduction in power corresponding to the injectionlevel controller becomes larger.

In this case, the injection level controller may change an injectionlevel between 3.0 dB and 10.0 dB in steps of 0.5 dB.

In this case, the enhanced layer signal may correspond to enhanced layerdata that is restored based on cancellation corresponding to therestoration of core layer data corresponding to the core layer signal.

In this case, the core layer BICM unit may include: a core layer errorcorrection encoder configured to perform error correction encoding onthe core layer data; a core layer bit interleaver configured to performbit interleaving corresponding to the core layer data; and a core layersymbol mapper configured to perform modulation corresponding to the corelayer data.

In this case, the enhanced layer BICM unit may include: an enhancedlayer error correction encoder configured to perform error correctionencoding on the enhanced layer data; an enhanced layer bit interleaverconfigured to perform bit interleaving corresponding to the enhancedlayer data; and an enhanced layer symbol mapper configured to performmodulation corresponding to the enhanced layer data.

In this case, the enhanced layer error correction encoder may have ahigher code rate than the core layer error correction encoder, and theenhanced layer symbol mapper may be less robust than the core layersymbol mapper.

In this case, the combiner may combine one or more extension layersignals, having lower power levels than the core layer signal and theenhanced layer signal, with the core layer signal and the enhanced layersignal.

Furthermore, an embodiment of the present invention provides a method ofgenerating broadcast signal frame, including: generating a multiplexedsignal by combining a core layer signal and an enhanced layer signal atdifferent power levels; reducing the power of the multiplexed signal toa power level corresponding to the core layer signal; generating atime-interleaved signal by performing interleaving that is applied toboth the core layer signal and the enhanced layer signal; and generatinga broadcast signal frame including a bootstrap and a preamble using thetime-interleaved signal.

In this case, the generating the broadcast signal frame may includegenerating the bootstrap; generating the preamble; and generating asuper-imposed payload corresponding to the time-interleaved signal.

In this case, the bootstrap may be shorter than the preamble, and have afixed-length.

In this case, the bootstrap may include a symbol representing astructure of the preamble, the symbol corresponding to a fixed-lengthbit string representing a combination of a modulation scheme/code rate,a FFT size, a guard interval length and a pilot pattern of the preamble.

In this case, the symbol may correspond to a lookup table in which apreamble structure corresponding to a second FFT size is allocated priorto a preamble structure corresponding to a first FFT size, the secondFFT size being less than the first FFT size when the modulationscheme/code rates are the same, and a preamble structure correspondingto a second guard interval length is allocated prior to a preamblestructure corresponding to a first guard interval length, the secondguard interval length being longer than the first guard interval lengthwhen the modulation scheme/code rates are the same and the FFT sizes arethe same.

In this case, the method may further include generating a power-reducedenhanced layer signal by reducing the power of the enhanced layersignal. In this case, the combining may include generating a multiplexedsignal by combining the core layer signal and the power-reduced enhancedlayer signal.

In this case, the method may further include generating signalinginformation including injection level information.

In this case, the reducing the power of the multiplexed signal mayinclude reducing the power of the multiplexed signal by a level by whichthe power has been increased by the combining.

In this case, the generating a power-reduced enhanced layer signal mayinclude changing an injection level between 3.0 dB and 10.0 dB in stepsof 0.5 dB.

In this case, the combining may include combining one or more extensionlayer signals, having lower power levels than the core layer signal andthe enhanced layer signal, with the core layer signal and the enhancedlayer signal.

Advantageous Effects

According to the present invention, a frame structure in which newsignal multiplexing technologies capable of providing greaterflexibility and performance than TDM and FDM is provided.

Furthermore, according to the present invention, multiple services canbe supported in a next generation broadcasting system at the same time,and also each of the services can use 100% of time and frequencyresources.

Furthermore, according to the present invention, signals correspondingto two or more layers can be efficiently multiplexed/demultiplexed bycombining the signals at respective different power levels.

DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a broadcast signaltransmission/reception system according to an embodiment of the presentinvention;

FIG. 2 is an operation flowchart showing a broadcast signaltransmission/reception method according to an embodiment of the presentinvention;

FIG. 3 is a block diagram showing an example of the apparatus forgenerating broadcast signal frame in FIG. 1 ;

FIG. 4 is a diagram showing an example of the structure of a broadcastsignal frame;

FIG. 5 is a diagram showing an example of the receiving process of thebroadcast signal frame shown in FIG. 4 ;

FIG. 6 is a diagram showing another example of the receiving process ofthe broadcast signal frame shown in FIG. 4 ;

FIG. 7 is a block diagram showing another example of the apparatus forgenerating broadcast signal frame shown in FIG. 1 ;

FIG. 8 is a block diagram showing an example of the signal demultiplexershown in FIG. 1 ;

FIG. 9 is a block diagram showing an example of the core layer BICMdecoder and the enhanced layer symbol extractor shown in FIG. 8 ;

FIG. 10 is a block diagram showing another example of the core layerBICM decoder and the enhanced layer symbol extractor shown in FIG. 8 ;

FIG. 11 is a block diagram showing still another example of the corelayer BICM decoder and the enhanced layer symbol extractor shown in FIG.8 ;

FIG. 12 is a block diagram showing another example of the signaldemultiplexer shown in FIG. 1 ;

FIG. 13 is a diagram showing an increase in power attributable to thecombination of a core layer signal and an enhanced layer signal; and

FIG. 14 is an operation flowchart showing a method of generatingbroadcast signal frame according to an embodiment of the presentinvention.

MODE FOR INVENTION

The present invention will be described in detail below with referenceto the accompanying drawings. In the description, redundant descriptionsand descriptions of well-known functions and configurations that havebeen deemed to make the gist of the present invention unnecessarilyobscure will be omitted below. The embodiments of the present inventionare provided to fully describe the present invention to persons havingordinary knowledge in the art to which the present invention pertains.Accordingly, the shapes, sizes, etc. of components in the drawings maybe exaggerated to make the description obvious.

Preferred embodiments of the present invention are described in detailbelow with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a broadcast signaltransmission/reception system according to an embodiment of the presentinvention.

Referring to FIG. 1 , a broadcast signal transmission/reception systemaccording to the embodiment of the present invention includes abroadcast signal transmission apparatus 110, a wireless channel 120, anda broadcast signal reception apparatus 130.

The broadcast signal transmission apparatus 110 includes an apparatusfor generating broadcast signal frame 111 which generate the broadcastsignal frame by multiplexing core layer data and enhanced layer data,and an OFDM transmitter 113.

The apparatus 111 combines a core layer signal corresponding to corelayer data and an enhanced layer signal corresponding to enhanced layerdata at different power levels, and generates a multiplexed signal byperforming interleaving that is applied to both the core layer signaland the enhanced layer signal. In this case, the apparatus 111 maygenerate a broadcast signal frame including a bootstrap and a preambleusing a time-interleaved signal. In this case, the broadcast signalframe may be an ATSC 3.0 frame.

The OFDM transmitter 113 transmits the multiplexed signal using an OFDMcommunication method via an antenna 117, thereby allowing thetransmitted OFDM signal to be received via the antenna 137 of thebroadcast signal reception apparatus 130 over the wireless channel 120.

The broadcast signal reception apparatus 130 includes an OFDM receiver133 and a signal demultiplexer 131. When the signal transmitted over thewireless channel 120 is received via the antenna 137, the OFDM receiver133 receives an OFDM signal via synchronization, channel estimation andequalization.

In this case, the OFDM receiver 133 may detect and demodulate thebootstrap from the OFDM signal, demodulate the preamble usinginformation included in the bootstrap, and demodulate the super-imposedpayload using information included in the preamble.

The signal demultiplexer 131 restores the core layer data from thesignal (super-imposed payload) received via the OFDM receiver 133 first,and then restores the enhanced layer data via cancellation correspondingto the restored core layer data. In this case, the signal demultiplexer131 may generate a broadcast signal frame first, may restore thebootstrap, may restore the preamble using the information included inthe bootstrap, and may use the signaling information included in thepreamble for the restoration of a data signal. In this case, thesignaling information may be L1 signaling information and may includeinjection level information, normalizing factor information, etc.

As will be described in detail later, the apparatus 111 shown in FIG. 1may include a combiner configured to generate a multiplexed signal bycombining a core layer signal and an enhanced layer signal at differentpower levels; a power normalizer configured to reduce the power of themultiplexed signal to a power level corresponding to the core layersignal; a time interleaver configured to generate a time-interleavedsignal by performing interleaving that is applied to both the core layersignal and the enhanced layer signal; and a frame builder configured togenerate a broadcast signal frame including a bootstrap and a preambleusing the time-interleaved signal. In this case, the broadcast signaltransmission apparatus 110 shown in FIG. 1 may be viewed as including: acombiner configured to generate a multiplexed signal by combining a corelayer signal and an enhanced layer signal at different power levels; apower normalizer configured to reduce the power of the multiplexedsignal to a power level corresponding to the core layer signal; a timeinterleaver configured to generate a time-interleaved signal byperforming interleaving that is applied to both the core layer signaland the enhanced layer signal; a frame builder configured to generate abroadcast signal frame including a boostrap and a preamble using thetime-interleaved signal; and an OFDM transmitter configured to transmitthe broadcast signal frame using OFDM communication scheme through anantenna.

As will be described in detail later, the signal demultiplexer shown inFIG. 1 may include a time deinterleaver configured to generate atime-deinterleaved signal by applying time deinterleaving to a receivedsignal corresponding to a broadcast signal frame; a de-normalizerconfigured to increase the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; a core layer BICMdecoder configured to restore core layer data from the signalpower-adjusted by the de-normalizer; an enhanced layer symbol extractorconfigured to extract an enhanced layer signal by performingcancellation corresponding to the core layer data on the signalpower-adjusted by the de-normalizer using the output signal of the corelayer FEC decoder of the core layer BICM decoder; a de-injection levelcontroller configured to increase the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and an enhanced layer BICM decoderconfigured to restore enhanced layer data using the output signal of thede-injection level controller. In this case, the broadcast signalreception apparatus 130 shown in FIG. 1 may be viewed as including: anOFDM receiver configured to generate a received signal by performing anyone or more of synchronization, channel estimation and equalization on atransmitted signal corresponding to a broadcast signal frame; a timedeinterleaver configured to generate a time-deinterleaved signal byapplying time deinterleaving to the received signal; a de-normalizerconfigured to increase the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; a core layer BICMdecoder configured to restore core layer data from the signalpower-adjusted by the de-normalizer; an enhanced layer symbol extractorconfigured to extract an enhanced layer signal by performingcancellation corresponding to the core layer data on the signalpower-adjusted by the de-normalizer using the output signal of the corelayer FEC decoder of the core layer BICM decoder; a de-injection levelcontroller configured to increase the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and an enhanced layer BICM decoderconfigured to restore enhanced layer data using the output signal of thede-injection level controller.

Although not explicitly shown in FIG. 1 , a broadcast signaltransmission/reception system according to an embodiment of the presentinvention may multiplex/demultiplex one or more pieces of extensionlayer data in addition to the core layer data and the enhanced layerdata. In this case, the extension layer data may be multiplexed at apower level lower than that of the core layer data and the enhancedlayer data. Furthermore, when two or more extension layers are included,the injection power level of a second extension layer may be lower thanthe injection power level of a first extension layer, and the injectionpower level of a third extension layer may be lower than the injectionpower level of the second extension layer.

FIG. 2 is an operation flowchart showing a broadcast signaltransmission/reception method according to an embodiment of the presentinvention.

Referring to FIG. 2 , in the broadcast signal transmission/receptionmethod according to the embodiment of the present invention, a corelayer signal and an enhanced layer signal are combined at differentpower levels and then multiplexed to generate a broadcast signal frameincluding a bootstrap and a preamble at step S210.

In this case, the broadcast signal frame generated at step S210 mayinclude the bootstrap, the preamble and a super-imposed payload. In thiscase, at least of the bootstrap and the preamble may include L1signaling information. In this case, the L1 signaling information mayinclude injection level information and normalizing factor information.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, the broadcastsignal frame is OFDM transmitted at step S220.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, the transmittedsignal is OFDM received at step S230.

In this case, at step S230, synchronization, channel estimation andequalization may be performed.

In this case, the bootstrap may be restored, the preamble may berestored using a signal included in the restored bootstrap, and the datasignal may be restored using the signaling information included in thepreamble at step S230.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, core layer data isrestored from the received signal at step S240.

Furthermore, in the broadcast signal transmission/reception methodaccording to the embodiment of the present invention, enhanced layerdata is restored via the cancellation of the core layer signal at stepS250.

In particular, steps S240 and S250 shown in FIG. 2 may correspond todemultiplexing operations corresponding to step S210.

As will be described in detail later, step S210 shown in FIG. 2 mayinclude generating a multiplexed signal by combining a core layer signaland an enhanced layer signal at different power levels; reducing thepower of the multiplexed signal to a power level corresponding to thecore layer signal; generating a time-interleaved signal by performinginterleaving that is applied to both the core layer signal and theenhanced layer signal; and generating a broadcast signal frame includinga bootstrap and a preamble using the time-interleaved signal.

In this case, the broadcast signal transmission method of steps S210 andS220 may be viewed as including generating a multiplexed signal bycombining a core layer signal and an enhanced layer signal at differentpower levels; reducing the power of the multiplexed signal to a powerlevel corresponding to the core layer signal; generating atime-interleaved signal by performing interleaving that is applied toboth the core layer signal and the enhanced layer signal; generating abroadcast signal frame including a bootstrap and a preamble using thetime-interleaved signal; and transmitting the broadcast signal frameusing an OFDM communication scheme through an antenna.

As will be described in detail later, steps S240 and S250 shown in FIG.2 may include generating a time-deinterleaved signal by applying timedeinterleaving to a received signal corresponding to a broadcast signalframe; increasing the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; restoring core layerdata from the power-adjusted signal; extracting an enhanced layer signalby performing cancellation corresponding to the core layer data on thepower-adjusted signal; increasing the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and restoring enhanced layer data usingthe power-adjusted enhanced signal. In this case, a broadcast signalreception method according to an embodiment of the present invention maybe viewed as including: generating a received signal by performing anyone or more of synchronization, channel estimation and equalization on atransmitted signal corresponding to a broadcast signal frame; generatinga time-deinterleaved signal by applying time deinterleaving to thereceived signal; increasing the power of the received signal or thetime-deinterleaved signal by a level corresponding to a reduction inpower by the power normalizer of the transmitter; restoring core layerdata from the power-adjusted signal; extracting an enhanced layer signalby performing cancellation corresponding to the core layer data on thepower-adjusted signal; increasing the power of the enhanced layer signalby a level corresponding to a reduction in power by the injection levelcontroller of the transmitter; and restoring enhanced layer data usingthe power-adjusted enhanced layer signal.

FIG. 3 is a block diagram showing an example of the apparatus forgenerating broadcast signal frame in FIG. 1 .

Referring to FIG. 3 , the apparatus for generating broadcast signalframe according to an embodiment of the present invention may include acore layer BICM unit 310, an enhanced layer BICM unit 320, an injectionlevel controller 330, a combiner 340, a power normalizer 345, and a timeinterleaver 350, a signaling generation unit 360, and a frame builder370.

Generally, a BICM device includes an error correction encoder, a bitinterleaver, and a symbol mapper. Each of the core layer BICM unit 310and the enhanced layer BICM unit 320 shown in FIG. 3 may include anerror correction encoder, a bit interleaver, and a symbol mapper. Inparticular, each of the error correction encoders (the core layer FECencoder, and the enhanced layer FEC encoder) shown in FIG. 3 may beformed by connecting a BCH encoder and an LDPC encoder in series. Inthis case, the input of the error correction encoder is input to the BCHencoder, the output of the BCH encoder is input to the LDPC encoder, andthe output of the LDPC encoder may be the output of the error correctionencoder.

As shown in FIG. 3 , core layer data and enhanced layer data passthrough respective different BICM units, and are then combined by thecombiner 340. That is, the term “Layered Division Multiplexing (LDM)”used herein may refer to combining the pieces of data of a plurality oflayers into a single piece of data using differences in power and thentransmitting the combined data.

That is, the core layer data passes through the core layer BICM unit310, the enhanced layer data passes through the enhanced layer BICM unit320 and then the injection level controller 330, and the core layer dataand the enhanced layer data are combined by the combiner 340. In thiscase, the enhanced layer BICM unit 320 may perform BICM encodingdifferent from that of the core layer BICM unit 310. That is, theenhanced layer BICM unit 320 may perform higher bit rate errorcorrection encoding or symbol mapping than the core layer BICM unit 310.Furthermore, the enhanced layer BICM unit 320 may perform less robusterror correction encoding or symbol mapping than the core layer BICMunit 310.

For example, the core layer error correction encoder may exhibit a lowerbit rate than the enhanced layer error correction encoder. In this case,the enhanced layer symbol mapper may be less robust than the core layersymbol mapper.

The combiner 340 may be viewed as functioning to combine the core layersignal and the enhanced layer signal at different power levels. In anembodiment, power level adjustment may be performed on the core layersignal rather than the enhanced layer signal. In this case, the power ofthe core layer signal may be adjusted to be higher than the power of theenhanced layer signal.

The core layer data may use forward error correction (FEC) code having alow code rate in order to perform robust reception, while the enhancedlayer data may use FEC code having a high code rate in order to achievea high data transmission rate.

That is, the core layer data may have a broader coverage than theenhanced layer data in the same reception environment.

The enhanced layer data having passed through the enhanced layer BICMunit 320 is adjusted in gain (or power) by the injection levelcontroller 330, and is combined with the core layer data by the combiner340.

That is, the injection level controller 330 generates a power-reducedenhanced layer signal by reducing the power of the enhanced layersignal. In this case, the magnitude of the signal adjusted by theinjection level controller 330 may be determined based on an injectionlevel. In this case, an injection level in the case where signal B isinserted into signal A may be defined by Equation 1 below:

$\begin{matrix}{{{Injectionlevel}({dB})} = {{- 10}{\log_{10}\left( \frac{{Signalpower}{of}B}{{Signalpower}{of}A} \right)}}} & (1)\end{matrix}$

For example, assuming that the injection level is 3 dB when the enhancedlayer signal is inserted into the core layer signal, Equation 1 meansthat the enhanced layer signal has power corresponding to half of thepower of the core layer signal.

In this case, the injection level controller 330 may adjust the powerlevel of the enhanced layer signal from 3.0 dB to 10.0 dB in steps of0.5 dB.

In general, transmission power that is assigned to the core layer ishigher than transmission power that is assigned to the enhanced layer,which enables the receiver to decode core layer data first.

In this case, the combiner 340 may be viewed as generating a multiplexedsignal by combining the core layer signal with the power-reducedenhanced layer signal.

The signal obtained by the combination of the combiner 340 is providedto the power normalizer 345 so that the power of the signal can bereduced by a power level corresponding to an increase in power caused bythe combination of the core layer signal and the enhanced layer signal,and then power adjustment is performed. That is, the power normalizer345 reduces the power of the signal, obtained by the multiplexing of thecombiner 340, to a power level corresponding to the core layer signal.Since the level of the combined signal is higher than the level of onelayer signal, the power normalizing of the power normalizer 345 isrequired in order to prevent amplitude clipping, etc. in the remainingportion of a broadcast signal transmission/reception system.

In this case, the power normalizer 345 may adjust the magnitude of thecombined signal to an appropriate value by multiplying the magnitude ofthe combined signal by the normalizing factor of Equation 2 below.Injection level information used to calculate Equation 2 below may betransferred to the power normalizer 345 via a signaling flow:

Normalizing factor=(√{square root over((1+10^(Injectionlevel(dB)/10)))})⁻¹  (2)

Assuming that the power levels of the core layer signal and the enhancedlayer signal are normalized to 1 when an enhanced layer signal S_(E) isinjected into a core layer signal S_(C) at a preset injection level, acombined signal may be expressed by S_(C)+αS_(E).

In this case, α is scaling factors corresponding to various injectionlevels. That is, the injection level controller 330 may correspond tothe scaling factor.

For example, when the injection level of an enhanced layer is 3 dB, acombined signal may be expressed by

$S_{C} + {\sqrt{\frac{1}{2}}{S_{E}.}}$

Since the power of a combined signal (a multiplexed signal) increasescompared to a core layer signal, the power normalizer 345 needs tomitigate the increase in power.

The output of the power normalizer 345 may be expressed byβ(S_(C)+αS_(E)).

In this case, β is normalizing factors based on various injection levelsof the enhanced layer.

When the injection level of the enhanced layer is 3 dB, the power of thecombined signal is increased by 50% compared to that of the core layersignal. Accordingly, the output of the power normalizer 345 may beexpressed by

$\sqrt{\frac{2}{3}}{\left( {S_{C} + {\sqrt{\frac{1}{2}}S_{E}}} \right).}$

Table 1 below lists scaling factors α and normalizing factors β forvarious injection levels (CL: Core Layer, EL: Enhanced Layer). Therelationships among the injection level, the scaling factor α and thenormalizing factor β may be defined by Equation 3 below:

$\begin{matrix}\left\{ \begin{matrix}{\alpha = 10^{(\frac{{- I}nje{ctionlevel}}{20})}} \\{\beta = \frac{1}{\sqrt{1 + \alpha^{2}}}}\end{matrix} \right. & (3)\end{matrix}$

TABLE 1 EL Injection level relative to CL Scaling factor α Normalizingfactor β  3.0 dB 0.7079458 0.8161736  3.5 dB 0.6683439 0.8314061  4.0 dB0.6309573 0.8457262  4.5 dB 0.5956621 0.8591327  5.0 dB 0.56234130.8716346  5.5 dB 0.5308844 0.8832495  6.0 dB 0.5011872 0.8940022  6.5dB 0.4731513 0.9039241  7.0 dB 0.4466836 0.9130512  7.5 dB 0.42169650.9214231  8.0 dB 0.3981072 0.9290819  8.5 dB 0.3758374 0.9360712  9.0dB 0.3548134 0.9424353  9.5 dB 0.3349654 0.9482180 10.0 dB 0.31622780.9534626

That is, the power normalizer 345 corresponds to the normalizing factor,and reduces the power of the multiplexed signal by a level by which thecombiner 340 has increased the power.

In this case, each of the normalizing factor and the scaling factor maybe a rational number that is larger than 0 and smaller than 1.

In this case, the scaling factor may decrease as a reduction in powercorresponding to the injection level controller 330 becomes larger, andthe normalizing factor may increase as a reduction in powercorresponding to the injection level controller 330 becomes larger.

The power normalized signal passes through the time interleaver 350 fordistributing burst errors occurring over a channel.

In this case, the time interleaver 350 may be viewed as performinginterleaving that is applied to both the core layer signal and theenhanced layer signal. That is, the core layer and the enhanced layershare the time interleaver, thereby preventing the unnecessary use ofmemory and also reducing latency at the receiver.

Although will be described later in greater detail, the enhanced layersignal may correspond to enhanced layer data restored based oncancellation corresponding to the restoration of core layer datacorresponding to the core layer signal. The combiner 340 may combine oneor more extension layer signals having power levels lower than those ofthe core layer signal and the enhanced layer signal with the core layersignal and the enhanced layer signal.

Meanwhile, L1 signaling information including injection levelinformation is encoded by the signaling generation unit 360 includingsignaling-dedicated BICM. In this case, the signaling generation unit360 may receive injection level information IL INFO from the injectionlevel controller 330, and may generate an L1 signaling signal.

In L1 signaling, L1 refers to Layer-1 in the lowest layer of the ISO 7layer model. In this case, the L1 signaling may be included in apreamble.

In general, the L1 signaling may include an FFT size, a guard intervalsize, etc., i.e., the important parameters of the OFDM transmitter, achannel code rate, modulation information, etc., i.e., BICM importantparameters. This L1 signaling signal is combined with data signal into abroadcast signal frame.

The frame builder 370 generates a broadcast signal frame by combiningthe L1 signaling signal with a data signal. In this case, the framebuilder 370 may generate the broadcast signal frame including abootstrap and a preamble using the time interleaved signal.

In this case, the frame builder 370 may include a bootstrap generatorconfigured to generate the bootstrap, a preamble generator configured togenerate the preamble, and a super-imposed payload generator configuredto generate a super-imposed payload corresponding to thetime-interleaved signal.

In this case, the bootstrap may be shorter than the preamble, and have afixed-length.

In this case, the bootstrap may include a symbol representing astructure of the preamble, the symbol corresponding to a fixed-lengthbit string representing a combination of a modulation scheme/code rate,a FFT size, a guard interval length and a pilot pattern of the preamble.

In this case, the symbol may correspond to a lookup table in which apreamble structure corresponding to a second FFT size is allocated priorto a preamble structure corresponding to a first FFT size, the secondFFT size being less than the first FFT size when the modulationscheme/code rates are the same, and a preamble structure correspondingto a second guard interval length is allocated prior to a preamblestructure corresponding to a first guard interval length, the secondguard interval length being longer than the first guard interval lengthwhen the modulation scheme/code rates are the same and the FFT sizes arethe same.

The broadcast signal frame may be transmitted via the OFDM transmitterthat is robust to a multi-path and the Doppler phenomenon. In this case,the OFDM transmitter may be viewed as being responsible for thetransmission signal generation of the next generation broadcastingsystem.

FIG. 4 is a diagram showing an example of the structure of a broadcastsignal frame.

Referring to FIG. 4 , a broadcast signal frame includes the bootstrap410, the preamble 420 and the super-imposed payload 430.

The frame shown in FIG. 4 , may be included in the super-frame.

In this case, the broadcast signal frame may include at least one ofOFDM symbols. The broadcast signal frame may include a reference symbolor a pilot symbol.

The frame structure in which the Layered Division Multiplexing (LDM) isapplied includes the bootstrap 410, the preamble 420 and thesuper-imposed payload 430 as shown in FIG. 4 .

In this case, the bootstrap 410 and the preamble 420 may be seen as thetwo hierarchical preambles.

In this case, the bootstrap 410 may have a shorter length than thepreamble 420 for the fast acquisition and detection. In this case, thebootstrap 410 may have a fixed-length. In this case, the bootstrap mayinclude a fixed-length symbol. For example, the bootstrap 410 mayconsist of four OFDM symbols each of which has 0.5 ms length so that thebootstrap 410 may correspond to the fixed time length of 2 ms.

In this case, the bootstrap 410 may have a fixed bandwidth, and thepreamble 420 and the super-imposed payload 430 may have a variablebandwidth wider than the bootstrap 410.

The preamble 420 may transmit detailed signaling information using arobust LDPC code. In this case, the length of the preamble 420 can bevaried according to the signaling information.

In this case, both the bootstrap 410 and the payload 430 may be seen asa common signal which is shared by a plurality of layers.

The super-imposed payload 430 may correspond to a multiplexed signal ofat least two layer signals. In this case, the super-imposed payload 430may be generated by combining a core layer payload and an enhanced layerpayload at different power levels. In this case, the core layer payloadmay include am in-band signaling section. In this case, the in-bandsignaling section may include signaling information for the enhancedlayer service.

In this case, the bootstrap 410 may include a symbol representing apreamble structure.

In this case, the symbol which included in the bootstrap forrepresenting the preamble structure may be set as shown in the Table 2below.

TABLE 2 Pilot Pattern preamble_structure L1-Basic Mode FFT Size GILength (samples) (DX) 0 L1-Basic Mode 1 8192 2048 3 1 L1-Basic Mode 18192 1536 4 2 L1-Basic Mode 1 8192 1024 3 3 L1-Basic Mode 1 8192 768 4 4L1-Basic Mode 1 16384 4096 3 5 L1-Basic Mode 1 16384 3648 4 6 L1-BasicMode 1 16384 2432 3 7 L1-Basic Mode 1 16384 1536 4 8 L1-Basic Mode 116384 1024 6 9 L1-Basic Mode 1 16384 768 8 10 L1-Basic Mode 1 32768 48643 11 L1-Basic Mode 1 32768 3648 3 12 L1-Basic Mode 1 32768 3648 8 13L1-Basic Mode 1 32768 2432 6 14 L1-Basic Mode 1 32768 1536 8 15 L1-BasicMode 1 32768 1024 12 16 L1-Basic Mode 1 32768 768 16 17 L1-Basic Mode 28192 2048 3 18 L1-Basic Mode 2 8192 1536 4 19 L1-Basic Mode 2 8192 10243 20 L1-Basic Mode 2 8192 768 4 21 L1-Basic Mode 2 16384 4096 3 22L1-Basic Mode 2 16384 3648 4 23 L1-Basic Mode 2 16384 2432 3 24 L1-BasicMode 2 16384 1536 4 25 L1-Basic Mode 2 16384 1024 6 26 L1-Basic Mode 216384 768 8 27 L1-Basic Mode 2 32768 4864 3 28 L1-Basic Mode 2 327683648 3 29 L1-Basic Mode 2 32768 3648 8 30 L1-Basic Mode 2 32768 2432 631 L1-Basic Mode 2 32768 1536 8 32 L1-Basic Mode 2 32768 1024 12 33L1-Basic Mode 2 32768 768 16 34 L1-Basic Mode 3 8192 2048 3 35 L1-BasicMode 3 8192 1536 4 36 L1-Basic Mode 3 8192 1024 3 37 L1-Basic Mode 38192 768 4 38 L1-Basic Mode 3 16384 4096 3 39 L1-Basic Mode 3 16384 36484 40 L1-Basic Mode 3 16384 2432 3 41 L1-Basic Mode 3 16384 1536 4 42L1-Basic Mode 3 16384 1024 6 43 L1-Basic Mode 3 16384 768 8 44 L1-BasicMode 3 32768 4864 3 45 L1-Basic Mode 3 32768 3648 3 46 L1-Basic Mode 332768 3648 8 47 L1-Basic Mode 3 32768 2432 6 48 L1-Basic Mode 3 327681536 8 49 L1-Basic Mode 3 32768 1024 12 50 L1-Basic Mode 3 32768 768 1651 L1-Basic Mode 4 8192 2048 3 52 L1-Basic Mode 4 8192 1536 4 53L1-Basic Mode 4 8192 1024 3 54 L1-Basic Mode 4 8192 768 4 55 L1-BasicMode 4 16384 4096 3 56 L1-Basic Mode 4 16384 3648 4 57 L1-Basic Mode 416384 2432 3 58 L1-Basic Mode 4 16384 1536 4 59 L1-Basic Mode 4 163841024 6 60 L1-Basic Mode 4 16384 768 8 61 L1-Basic Mode 4 32768 4864 3 62L1-Basic Mode 4 32768 3648 3 63 L1-Basic Mode 4 32768 3648 8 64 L1-BasicMode 4 32768 2432 6 65 L1-Basic Mode 4 32768 1536 8 66 L1-Basic Mode 432768 1024 12 67 L1-Basic Mode 4 32768 768 16 68 L1-Basic Mode 5 81922048 3 69 L1-Basic Mode 5 8192 1536 4 70 L1-Basic Mode 5 8192 1024 3 71L1-Basic Mode 5 8192 768 4 72 L1-Basic Mode 5 16384 4096 3 73 L1-BasicMode 5 16384 3648 4 74 L1-Basic Mode 5 16384 2432 3 75 L1-Basic Mode 516384 1536 4 76 L1-Basic Mode 5 16384 1024 6 77 L1-Basic Mode 5 16384768 8 78 L1-Basic Mode 5 32768 4864 3 79 L1-Basic Mode 5 32768 3648 3 80L1-Basic Mode 5 32768 3648 8 81 L1-Basic Mode 5 32768 2432 6 82 L1-BasicMode 5 32768 1536 8 83 L1-Basic Mode 5 32768 1024 12 84 L1-Basic Mode 532768 768 16 85 L1-Basic Mode 6 8192 2048 3 86 L1-Basic Mode 6 8192 15364 87 L1-Basic Mode 6 8192 1024 3 88 L1-Basic Mode 6 8192 768 4 89L1-Basic Mode 6 16384 4096 3 90 L1-Basic Mode 6 16384 3648 4 91 L1-BasicMode 6 16384 2432 3 92 L1-Basic Mode 6 16384 1536 4 93 L1-Basic Mode 616384 1024 6 94 L1-Basic Mode 6 16384 768 8 95 L1-Basic Mode 6 327684864 3 96 L1-Basic Mode 6 32768 3648 3 97 L1-Basic Mode 6 32768 3648 898 L1-Basic Mode 6 32768 2432 6 99 L1-Basic Mode 6 32768 1536 8 100L1-Basic Mode 6 32768 1024 12 101 L1-Basic Mode 6 32768 768 16 102L1-Basic Mode 7 8192 2048 3 103 L1-Basic Mode 7 8192 1536 4 104 L1-BasicMode 7 8192 1024 3 105 L1-Basic Mode 7 8192 768 4 106 L1-Basic Mode 716384 4096 3 107 L1-Basic Mode 7 16384 3648 4 108 L1-Basic Mode 7 163842432 3 109 L1-Basic Mode 7 16384 1536 4 110 L1-Basic Mode 7 16384 1024 6111 L1-Basic Mode 7 16384 768 8 112 L1-Basic Mode 7 32768 4864 3 113L1-Basic Mode 7 32768 3648 3 114 L1-Basic Mode 7 32768 3648 8 115L1-Basic Mode 7 32768 2432 6 116 L1-Basic Mode 7 32768 1536 8 117L1-Basic Mode 7 32768 1024 12 118 L1-Basic Mode 7 32768 768 16 119Reserved Reserved Reserved Reserved 120 Reserved Reserved ReservedReserved 121 Reserved Reserved Reserved Reserved 122 Reserved ReservedReserved Reserved 123 Reserved Reserved Reserved Reserved 124 ReservedReserved Reserved Reserved 125 Reserved Reserved Reserved Reserved 126Reserved Reserved Reserved Reserved 127 Reserved Reserved ReservedReserved

For example, a fixed-length symbol 7-bit may be assigned or representingthe preamble structure shown in the Table 2.

The L1-Basic Mode 1, L1-Basic Mode 2 and L1-Basic Mode 3 in the Table 2may correspond to QPSK and 3/15 LDPC.

The L1 Basic Mode 4 in the Table 2 may correspond to 16-NUC (Non UniformConstellation) and 3/15 LDPC.

The L1 Basic Mode 5 in the Table 2 may correspond to 64-NUC (Non UniformConstellation) and 3/15 LDPC.

The L1-Basic Mode 6 and L1-Basic Mode 7 in the Table 2 may correspond to256-NUC (Non Uniform Constellation) and 3/15 LDPC. Hereafter, themodulation scheme/code rate represents a combination of a modulationscheme and a code rate such as QPSK and 3/15 LDPC.

The FFT size in the Table 2 may represent a size of Fast FourierTransform.

The GI length in the Table 2 may represent the Guard Interval Length,may represent a length of the guard interval which is not data in a timedomain. In this case, the guard interval is longer, the system is morerobust.

The Pilot Pattern in the Table 2 may represent Dx of the pilot pattern.Although it is not shown in the Table 2 explicitly, Dy may be all 1 inthe example of Table 2. For example, Dx=3 may mean that one pilot forchannel estimation is included in x-axis direction in every threesymbols. For example, Dy=1 may mean the pilot is included every time iny-axis direction.

As shown in the Table 2, the preamble structure corresponding to asecond modulation scheme/code rate which is more robust than a firstmodulation scheme/code rate may be allocated in the lookup table priorto the preamble structure corresponding to the first modulationscheme/code rate.

In this case, the being allocated prior to other preamble structure maymean being stored in the lookup table corresponding to a serial numberless than the serial number of the other preamble structure.

Furthermore, the preamble structure corresponding to a second FFT sizewhich is shorter than a first FFT size may be allocated in the lookuptable prior to the preamble structure corresponding to a first FFT sizein case of the same modulation scheme/code rate.

Furthermore, the preamble structure corresponding to a second guardinterval which is longer than a first guard interval may be allocated inthe lookup table prior to the preamble structure corresponding to thefirst guard interval in case of the same modulation scheme/code rate andthe same FFT size.

As shown in the Table 2, the setting of the order in which the preamblestructures are assigned in the lookup table may make the recognition ofthe preamble structure using the bootstrap more efficient.

FIG. 5 is a diagram showing an example of the receiving process of thebroadcast signal frame shown in FIG. 4 .

Referring to FIG. 5 , the bootstrap 510 is detected and demodulated, andthe signaling information is reconstructed by the demodulation of thepreamble 520 using the demodulated information.

The core layer data 530 is demodulated using the signaling informationand the enhanced layer signal is demodulated through the cancellationprocess corresponding to the core layer data. In this case, thecancellation corresponding to the core layer data will be described indetail later.

FIG. 6 is a diagram showing another example of the receiving process ofthe broadcast signal frame shown in FIG. 4 .

Referring to FIG. 6 , the bootstrap 610 is detected and demodulated, andthe signaling information is reconstructed by the demodulation of thepreamble 620 using the demodulated information.

The core layer data 630 is demodulated using the signaling information.In this case, the core layer data 630 includes in-band signaling section650. The in-band signaling section 650 includes signaling informationfor the enhanced layer service. The bandwidth is used more efficientlythrough the in-band signaling section 650. In this case, the in-bandsignaling section 650 may be included in the core layer which is morerobust than the enhanced layer.

The basic signaling information and the information for the core layerservice may be transferred through the preamble 620 and the signalinginformation for the enhanced layer service may be transferred throughthe in-band signaling section 650 in the example of the FIG. 6 .

The enhanced layer signal is demodulated through the cancellationprocess corresponding to the core layer data.

In this case, the signaling information may be L1 (Layer-1) signalinginformation. The L1 signaling information may include information forphysical layer parameters.

Referring to FIG. 4 , a broadcast signal frame includes an L1 signalingsignal and a data signal. For example, the broadcast signal frame may bean ATSC 3.0 frame.

FIG. 7 is a block diagram showing another example of the apparatus forgenerating broadcast signal frame shown in FIG. 1 .

Referring to FIG. 7 , it can be seen that an apparatus for generatingbroadcast signal frame multiplexes data corresponding to N (N is anatural number that is equal to or larger than 1) extension layerstogether in addition to core layer data and enhanced layer data.

That is, the apparatus for generating the broadcast signal frame in FIG.7 includes N extension layer BICM units 410, . . . , 430 and injectionlevel controllers 440, . . . , 460 in addition to a core layer BICM unit310, an enhanced layer BICM unit 320, an injection level controller 330,a combiner 340, a power normalizer 345, a time interleaver 350, asignaling generation unit 360, and a frame builder 370.

The core layer BICM unit 310, enhanced layer BICM unit 320, injectionlevel controller 330, combiner 340, power normalizer 345, timeinterleaver 350, signaling generation unit 360 and frame builder 370shown in FIG. 7 have been described in detail with reference to FIG. 3 .

Each of the N extension layer BICM units 410, . . . , 430 independentlyperforms BICM encoding, and each of the injection level controllers 440,. . . , 460 performs power reduction corresponding to a correspondingextension layer, thereby enabling a power reduced extension layer signalto be combined with other layer signals via the combiner 340.

In this case, each of the error correction encoders of the extensionlayer BICM units 410, . . . , 430 may be formed by connecting a BCHencoder and an LDPC encoder in series.

In particular, it is preferred that a reduction in power correspondingto each of the injection level controllers 440, . . . , 460 be higherthan the reduction in power of the injection level controller 330. Thatis, a lower one of the injection level controllers 330, 440, . . . , 460shown in FIG. 7 may correspond to a larger reduction in power.

Injection level information provided by the injection level controllers330, 440 and 460 shown in FIG. 7 is included in the broadcast signalframe of the frame builder 370 via the signaling generation unit 360,and is then transmitted to the receiver. That is, the injection level ofeach layer is contained in the L1 signaling information and thentransferred to the receiver.

In the present invention, the adjustment of power may correspond toincreasing or decreasing the power of an input signal, and maycorrespond to increasing or decreasing the gain of an input signal.

The power normalizer 345 mitigates an increase in power caused by thecombination of a plurality of layer signals by means of the combiner340.

In the example shown in FIG. 7 , the power normalizer 345 may adjust thepower of a signal to appropriate magnitude by multiplying the magnitudeof a signal, into which the signals of the respective layers arecombined, by a normalizing factor by using Equation 4 below:

$\begin{matrix}{{{Normalizing}{factor}} = \left( \sqrt{\begin{matrix}\begin{matrix}\left( {1 + {10^{‐{{Injectionlevel}{\# 1}{{({dB})}/1}0}}} +} \right. \\{10^{‐{{Injectionlevel}{\# 2}{{({dB})}/1}0}} + \ldots +}\end{matrix} \\\left. 10^{‐{{Injectionlevel}\#{({N + 1})}{{({dB})}/1}0}} \right)\end{matrix}} \right)^{- 1}} & (4)\end{matrix}$

The time interleaver 350 performs interleaving equally applied to thesignals of the layers by interleaving the signals combined by thecombiner 340.

FIG. 8 is a block diagram showing still an example of the signaldemultiplexer shown in FIG. 1 .

Referring to FIG. 8 , a signal demultiplexer according to an embodimentof the present invention includes a time deinterleaver 510, ade-normalizer 1010, core layer BICM decoder 520, an enhanced layersymbol extractor 530, a de-injection level controller 1020, and anenhanced layer BICM decoder 540.

In this case, the signal demultiplexer shown in FIG. 8 may correspond tothe apparatus for generating the broadcast signal frame shown in FIG. 3.

The time deinterleaver 510 receives a received signal from an OFDMreceiver for performing operations, such as time/frequencysynchronization, channel estimation and equalization, and performs anoperation related to the distribution of burst errors occurring over achannel. In this case, the L1 signaling information is decoded by theOFDM receiver first, and is then used for the decoding of data. Inparticular, the injection level information of the L1 signalinginformation may be transferred to the de-normalizer 1010 and thede-injection level controller 1020. In this case, the OFDM receiver maydecode the received signal in the form of a broadcast signal frame, forexample, an ATSC 3.0 frame, may extract the data symbol part of theframe, and may provide the extracted data symbol part to the timedeinterleaver 510. That is, the time deinterleaver 510 distributes bursterrors occurring over a channel by performing deinterleaving whilepassing a data symbol therethrough.

The de-normalizer 1010 corresponds to the power normalizer of thetransmitter, and increases power by a level by which the powernormalizer has decreased the power. That is, the de-normalizer 1010divides the received signal by the normalizing factor of Equation 2.

Although the de-normalizer 1010 is illustrated as adjusting the power ofthe output signal of the time interleaver 510 in the example shown inFIG. 8 , the de-normalizer 1010 may be located before the timeinterleaver 510 so that power adjustment is performed beforeinterleaving in some embodiments.

That is, the de-normalizer 1010 may be viewed as being located before orafter the time interleaver 510 and amplifying the magnitude of a signalfor the purpose of the LLR calculation of the core layer symboldemapper.

The output of the time deinterleaver 510 (or the output of thede-normalizer 1010) is provided to the core layer BICM decoder 520, andthe core layer BICM decoder 520 restores core layer data.

In this case, the core layer BICM decoder 520 includes a core layersymbol demapper, a core layer bit deinterleaver, and a core layer errorcorrection decoder. The core layer symbol demapper calculates LLR valuesrelated to symbols, the core layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the core layer errorcorrection decoder corrects error occurring over a channel.

In this case, the core layer symbol demapper may calculate an LLR valuefor each bit using a predetermined constellation. In this case, theconstellation used by the core layer symbol mapper may vary depending onthe combination of the code rate and the modulation order that are usedby the transmitter.

In this case, the core layer bit deinterleaver may performdeinterleaving on calculated LLR values on an LDPC code word basis.

In particular, the core layer error correction decoder may output onlyinformation bits, or may output all bits in which information bits havebeen mixed with parity bits. In this case, the core layer errorcorrection decoder may output only information bits as core layer data,and may output all bits in which information bits have been mixed withparity bits to the enhanced layer symbol extractor 530.

The core layer error correction decoder may be formed by connecting acore layer LDPC decoder and a core layer BCH decoder in series. That is,the input of the core layer error correction decoder may be input to thecore layer LDPC decoder, the output of the core layer LDPC decoder maybe input to the core layer BCH decoder, and the output of the core layerBCH decoder may become the output of the core layer error correctiondecoder. In this case, the LDPC decoder performs LDPC decoding, and theBCH decoder performs BCH decoding.

Furthermore, the enhanced layer error correction decoder may be formedby connecting an enhanced layer LDPC decoder and an enhanced layer BCHdecoder in series. That is, the input of the enhanced layer errorcorrection decoder may be input to the enhanced layer LDPC decoder, theoutput of the enhanced layer LDPC decoder may be input to the enhancedlayer BCH decoder, and the output of the enhanced layer BCH decoder maybecome the output of the enhanced layer error correction decoder.

The enhanced layer symbol extractor 530 may receive all bits from thecore layer error correction decoder of the core layer BICM decoder 520,may extract enhanced layer symbols from the output signal of the timedeinterleaver 510 or de-normalizer 1010. In an embodiment, the enhancedlayer symbol extractor 530 may not be provided with all bits by theerror correction decoder of the core layer BICM decoder 520, but may beprovided with LDPC information bits or BCH information bits by the errorcorrection decoder of the core layer BICM decoder 520.

In this case, the enhanced layer symbol extractor 530 includes a buffer,a subtracter, a core layer symbol mapper, and a core layer bitinterleaver. The buffer stores the output signal of the timedeinterleaver 510 or de-normalizer 1010. The core layer bit interleaverreceives the all bits (information bits+parity bits) of the core layerBICM decoder, and performs the same core layer bit interleaving as thetransmitter. The core layer symbol mapper generates core layer symbols,which are the same as the transmitter, from the interleaved signal. Thesubtracter obtains enhanced layer symbols by subtracting the outputsignal of the core layer symbol mapper from the signal stored in thebuffer, and transfers the enhanced layer symbols to the de-injectionlevel controller 1020. In particular, when LDPC information bits areprovided, the enhanced layer symbol extractor 530 may further include acore layer LDPC encoder. Furthermore, when BCH information bits areprovided, the enhanced layer symbol extractor 530 may further includenot only a core layer LDPC encoder but also a core layer BCH encoder.

In this case, the core layer LDPC encoder, core layer BCH encoder, corelayer bit interleaver and core layer symbol mapper included in theenhanced layer symbol extractor 530 may be the same as the LDPC encoder,BCH encoder, bit interleaver and symbol mapper of the core layerdescribed with reference to FIG. 3 .

The de-injection level controller 1020 receives the enhanced layersymbols, and increases the power of the input signal by a level by whichthe injection level controller of the transmitter has decreased thepower. That is, the de-injection level controller 1020 amplifies theinput signal, and provides the amplified input signal to the enhancedlayer BICM decoder 540. For example, if at the transmitter, the powerused to combine the enhanced layer signal is lower than the power usedto combine the core layer signal by 3 dB, the de-injection levelcontroller 1020 functions to increase the power of the input signal by 3dB.

In this case, the de-injection level controller 1020 may be viewed asreceiving injection level information from the OFDM receiver andmultiplying an extracted enhanced layer signal by the enhanced layergain of Equation 5:

Enhanced layer gain=(√{square root over(10^(Injectionlevel(dB)/10))})⁻¹  (5)

The enhanced layer BICM decoder 540 receives the enhanced layer symbolwhose power has been increased by the de-injection level controller1020, and restores the enhanced layer data.

In this case, the enhanced layer BICM decoder 540 may include anenhanced layer symbol demapper, an enhanced layer bit deinterleaver, andan enhanced layer error correction decoder. The enhanced layer symboldemapper calculates LLR values related to the enhanced layer symbols,the enhanced layer bit deinterleaver strongly mixes the calculated LLRvalues with burst errors, and the enhanced layer error correctiondecoder corrects error occurring over a channel.

Although the enhanced layer BICM decoder 540 performs a task similar toa task that is performed by the core layer BICM decoder 520, theenhanced layer LDPC decoder generally performs LDPC decoding related toa code rate equal to or higher than 6/15.

For example, the core layer may use LDPC code having a code rate equalto or higher than 5/15, and the enhanced layer may use LDPC code havinga code rate equal to or higher than 6/15. In this case, in a receptionenvironment in which enhanced layer data can be decoded, core layer datamay be decoded using only a small number of LDPC decoding iterations.Using this characteristic, in the hardware of the receiver, a singleLDPC decoder is shared by the core layer and the enhanced layer, andthus the cost required to implement the hardware can be reduced. In thiscase, the core layer LDPC decoder may use only some time resources (LDPCdecoding iterations), and the enhanced layer LDPC decoder may use mosttime resources.

That is, the signal demultiplexer shown in FIG. 8 restores core layerdata first, leaves only the enhanced layer symbols by cancellation thecore layer symbols in the received signal symbols, and then restoresenhanced layer data by increasing the power of the enhanced layersymbols. As described with reference to FIGS. 3 and 5 , signalscorresponding to respective layers are combined at different powerlevels, and thus data restoration having the smallest error can beachieved only if restoration starts with a signal combined with thestrongest power.

Accordingly, in the example shown in FIG. 8 , the signal demultiplexermay include the time deinterleaver 510 configured to generate atime-deinterleaved signal by applying time deinterleaving to a receivedsignal; a de-normalizer 1010 configured to increase the power of thereceived signal or the time-deinterleaved signal by a levelcorresponding to a reduction in power by the power normalizer of thetransmitter; the core layer BICM decoder 520 configured to restore corelayer data from the signal power-adjusted by the de-normalizer 1010; theenhanced layer symbol extractor 530 configured to extract an enhancedlayer signal by performing cancellation, corresponding to the core layerdata, on the signal power-adjusted by the de-normalizer 1010 using theoutput signal of the core layer FEC decoder of the core layer BICMdecoder 520; a de-injection level controller 1020 configured to increasethe power of the enhanced layer signal by a level corresponding to areduction in power by the injection power level controller of thetransmitter; and an enhanced layer BICM decoder 540 configured torestore enhanced layer data using the output signal of the de-injectionlevel controller 1020.

In this case, the enhanced layer symbol extractor may receive all codewords from the core layer LDPC decoder of the core layer BICM decoder,and may immediately perform bit interleaving on the all code words.

In this case, the enhanced layer symbol extractor may receiveinformation bits from the core layer LDPC decoder of the core layer BICMdecoder, and may perform core layer LDPC encoding and then bitinterleaving on the information bits.

In this case, the enhanced layer symbol extractor may receiveinformation bits from the core layer BCH decoder of the core layer BICMdecoder, and may perform core layer BCH encoding and core layer LDPCencoding and then bit interleaving on the information bits.

In this case, the de-normalizer and the de-injection level controllermay receive injection level information IL INFO provided based on L1signaling, and may perform power control based on the injection levelinformation.

In this case, the core layer BICM decoder may have a bit rate lower thanthat of the enhanced layer BICM decoder, and may be more robust than theenhanced layer BICM decoder.

In this case, the de-normalizer may correspond to the reciprocal of thenormalizing factor.

In this case, the de-injection level controller may correspond to thereciprocal of the scaling factor.

In this case, the enhanced layer data may be restored based oncancellation corresponding to the restoration of core layer datacorresponding to the core layer signal.

In this case, the signal demultiplexer further may include one or moreextension layer symbol extractors each configured to extract anextension layer signal by performing cancellation corresponding toprevious layer data; one or more de-injection level controllers eachconfigured to increase the power of the extension layer signal by alevel corresponding to a reduction in power by the injection levelcontroller of the transmitter; and one or more extension layer BICMdecoders configured to restore one or more pieces of extension layerdata using the output signals of the one or more de-injection levelcontrollers.

From the configuration shown in FIG. 8 , it can be seen that a signaldemultiplexing method according to an embodiment of the presentinvention includes generating a time-deinterleaved signal by applyingtime deinterleaving to a received signal; increasing the power of thereceived signal or the time-deinterleaved signal by a levelcorresponding to a reduction in power by the power normalizer of thetransmitter; restoring core layer data from the power-adjusted signal;extracting an enhanced layer signal by performing cancellation,corresponding to the core layer data, on the power-adjusted signal;increasing the power of the enhanced layer signal by a levelcorresponding to a reduction in power by the injection power levelcontroller of the transmitter; and restoring enhanced layer data usingthe enhanced layer data.

In this case, extracting the enhanced layer signal may include receivingall code words from the core layer LDPC decoder of the core layer BICMdecoder, and immediately performing bit interleaving on the all codewords.

In this case, extracting the enhanced layer signal may include receivinginformation bits from the core layer LDPC decoder of the core layer BICMdecoder, and performing core layer LDPC encoding and then bitinterleaving on the information bits.

In this case, extracting the enhanced layer signal may include receivinginformation bits from the core layer BCH decoder of the core layer BICMdecoder, and performing core layer BCH encoding and core layer LDPCencoding and then bit interleaving on the information bits.

FIG. 9 is a block diagram showing an example of the core layer BICMdecoder 520 and the enhanced layer symbol extractor 530 shown in FIG. 8.

Referring to FIG. 9 , the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 9 , the core layer errorcorrection decoder includes the core layer LDPC decoder and the corelayer BCH decoder.

Furthermore, in the example shown in FIG. 9 , the core layer LDPCdecoder provides all code words, including parity bits, to the enhancedlayer symbol extractor 530. That is, although the LDPC decoder generallyoutputs only the information bits of all the LDPC code words, the LDPCdecoder may output all the code words.

In this case, although the enhanced layer symbol extractor 530 may beeasily implemented because it does not need to include a core layer LDPCencoder or a core layer BCH encoder, there is a possibility that aresidual error may remain in the LDPC code parity part.

FIG. 10 is a block diagram showing another example of the core layerBICM decoder 520 and the enhanced layer symbol extractor 530 shown inFIG. 8 .

Referring to FIG. 10 , the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 10 , the core layer errorcorrection decoder includes the core layer LDPC decoder and the corelayer BCH decoder.

Furthermore, in the example shown in FIG. 10 , the core layer LDPCdecoder provides information bits, excluding parity bits, to theenhanced layer symbol extractor 530.

In this case, although the enhanced layer symbol extractor 530 does notneed to include a core layer BCH encoder, it must include a core layerLDPC encoder.

A residual error that may remain in the LDPC code parity part may beeliminated more desirably in the example shown in FIG. 10 than in theexample shown in FIG. 9 .

FIG. 11 is a block diagram showing still another example of the corelayer BICM decoder 520 and the enhanced layer symbol extractor 530 shownin FIG. 8 .

Referring to FIG. 11 , the core layer BICM decoder 520 includes a corelayer symbol demapper, a core layer bit deinterleaver, a core layer LDPCdecoder, and a core layer BCH decoder.

That is, in the example shown in FIG. 11 , the core layer errorcorrection decoder includes the core layer LDPC decoder and the corelayer BCH decoder.

In the example shown in FIG. 11 , the output of the core layer BCHdecoder corresponding to core layer data is provided to the enhancedlayer symbol extractor 530.

In this case, although the enhanced layer symbol extractor 530 has highcomplexity because it must include both a core layer LDPC encoder and acore layer BCH encoder, it guarantees higher performance than those inthe examples of FIGS. 9 and 10 .

FIG. 12 is a block diagram showing another example of the signaldemultiplexer shown in FIG. 1 .

Referring to FIG. 12 , a signal demultiplexer according to an embodimentof the present invention includes a time deinterleaver 510, ade-normalizer 1010, a core layer BICM decoder 520, an enhanced layersymbol extractor 530, an enhanced layer BICM decoder 540, one or moreextension layer symbol extractors 650 and 670, one or more extensionlayer BICM decoders 660 and 680, and de-injection level controllers1020, 1150 and 1170.

In this case, the signal demultiplexer shown in FIG. 12 may correspondto the apparatus for generating broadcast signal frame shown in FIG. 7 .

The time deinterleaver 510 receives a received signal from an OFDMreceiver for performing operations, such as synchronization, channelestimation and equalization, and performs an operation related to thedistribution of burst errors occurring over a channel. In this case, L1signaling information may be decoded by the OFDM receiver first, andthen may be used for data decoding. In particular, the injection levelinformation of the L1 signaling information may be transferred to thede-normalizer 1010 and the de-injection level controllers 1020, 1150 and1170.

In this case, the de-normalizer 1010 may obtain the injection levelinformation of all layers, may obtain a de-normalizing factor usingEquation 6 below, and may multiply the input signal with thede-normalizing factor:

$\begin{matrix}{{De}‐{{{normalizing}{factor}} = \left( \sqrt{\begin{matrix}\begin{matrix}\left( {1 + {10^{‐{{Injectionlevel}{\# 1}{{({dB})}/1}0}}} +} \right. \\{10^{‐{{Injectionlevel}{\# 2}{{({dB})}/1}0}} + \ldots +}\end{matrix} \\\left. 10^{‐{{Injectionlevel}\#{({N + 1})}{{({dB})}/1}0}} \right)\end{matrix}} \right)^{- 1}}} & (6)\end{matrix}$

That is, the de-normalizing factor is the reciprocal of the normalizingfactor expressed by Equation 4 above.

In an embodiment, when the N1 signaling includes not only injectionlevel information but also normalizing factor information, thede-normalizer 1010 may simply obtain a de-normalizing factor by takingthe reciprocal of a normalizing factor without the need to calculate thede-normalizing factor using an injection level.

The de-normalizer 1010 corresponds to the power normalizer of thetransmitter, and increases power by a level by which the powernormalizer has decreased the power.

Although the de-normalizer 1010 is illustrated as adjusting the power ofthe output signal of the time interleaver 510 in the example shown inFIG. 12 , the de-normalizer 1010 may be located before the timeinterleaver 510 so that power adjustment can be performed beforeinterleaving in an embodiment.

That is, the de-normalizer 1010 may be viewed as being located before orafter the time interleaver 510 and amplifying the magnitude of a signalfor the purpose of the LLR calculation of the core layer symboldemapper.

The output of the time deinterleaver 510 (or the output of thede-normalizer 1010) is provided to the core layer BICM decoder 520, andthe core layer BICM decoder 520 restores core layer data.

In this case, the core layer BICM decoder 520 includes a core layersymbol demapper, a core layer bit deinterleaver, and a core layer errorcorrection decoder. The core layer symbol demapper calculates LLR valuesrelated to symbols, the core layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the core layer errorcorrection decoder corrects error occurring over a channel.

In particular, the core layer error correction decoder may output onlyinformation bits, or may output all bits in which information bits havebeen combined with parity bits. In this case, the core layer errorcorrection decoder may output only information bits as core layer data,and may output all bits in which information bits have been combinedwith parity bits to the enhanced layer symbol extractor 530.

The core layer error correction decoder may be formed by connecting acore layer LDPC decoder and a core layer BCH decoder in series. That is,the input of the core layer error correction decoder may be input to thecore layer LDPC decoder, the output of the core layer LDPC decoder maybe input to the core layer BCH decoder, and the output of the core layerBCH decoder may become the output of the core layer error correctiondecoder. In this case, the LDPC decoder performs LDPC decoding, and theBCH decoder performs BCH decoding.

The enhanced layer error correction decoder may be also formed byconnecting an enhanced layer LDPC decoder and an enhanced layer BCHdecoder in series. That is, the input of the enhanced layer errorcorrection decoder may be input to the enhanced layer LDPC decoder, theoutput of the enhanced layer LDPC decoder may be input to the enhancedlayer BCH decoder, and the output of the enhanced layer BCH decoder maybecome the output of the enhanced layer error correction decoder.

Moreover, the extension layer error correction decoder may be alsoformed by connecting an extension layer LDPC decoder and an extensionlayer BCH decoder in series. That is, the input of the extension layererror correction decoder may be input to the extension layer LDPCdecoder, the output of the extension layer LDPC decoder may be input tothe extension layer BCH decoder, and the output of the extension layerBCH decoder may become the output of the extension layer errorcorrection decoder.

In particular, the tradeoff between the complexity of implementation,regarding which of the outputs of the error correction decoders will beused, which has been described with reference to FIGS. 9, 10 and 11 ,and performance is applied to not only the core layer BICM decoder 520and enhanced layer symbol extractor 530 of FIG. 12 but also theextension layer symbol extractors 650 and 670 and the extension layerBICM decoders 660 and 680.

The enhanced layer symbol extractor 530 may receive the all bits fromthe core layer BICM decoder 520 of the core layer error correctiondecoder, and may extract enhanced layer symbols from the output signalof the time deinterleaver 510 or the denormalizer 1010. In anembodiment, the enhanced layer symbol extractor 530 may not receive allbits from the error correction decoder of the core layer BICM decoder520, but may receive LDPC information bits or BCH information bits.

In this case, the enhanced layer symbol extractor 530 includes a buffer,a subtracter, a core layer symbol mapper, and a core layer bitinterleaver. The buffer stores the output signal of the timedeinterleaver 510 or de-normalizer 1010. The core layer bit interleaverreceives the all bits (information bits+parity bits) of the core layerBICM decoder, and performs the same core layer bit interleaving as thetransmitter. The core layer symbol mapper generates core layer symbols,which are the same as the transmitter, from the interleaved signal. Thesubtracter obtains enhanced layer symbols by subtracting the outputsignal of the core layer symbol mapper from the signal stored in thebuffer, and transfers the enhanced layer symbols to the de-injectionlevel controller 1020.

In this case, the core layer bit interleaver and core layer symbolmapper included in the enhanced layer symbol extractor 530 may be thesame as the core layer bit interleaver and the core layer symbol mappershown in FIG. 7 .

The de-injection level controller 1020 receives the enhanced layersymbols, and increases the power of the input signal by a level by whichthe injection level controller of the transmitter has decreased thepower. That is, the de-injection level controller 1020 amplifies theinput signal, and provides the amplified input signal to the enhancedlayer BICM decoder 540.

The enhanced layer BICM decoder 540 receives the enhanced layer symbolwhose power has been increased by the de-injection level controller1020, and restores the enhanced layer data.

In this case, the enhanced layer BICM decoder 540 may include anenhanced layer symbol demapper, an enhanced layer bit deinterleaver, andan enhanced layer error correction decoder. The enhanced layer symboldemapper calculates LLR values related to the enhanced layer symbols,the enhanced layer bit deinterleaver strongly mixes the calculated LLRvalues with burst errors, and the enhanced layer error correctiondecoder corrects error occurring over a channel.

In particular, the enhanced layer error correction decoder may outputonly information bits, and may output all bits in which information bitshave been combined with parity bits. In this case, the enhanced layererror correction decoder may output only information bits as enhancedlayer data, and may output all bits in which information bits have beenmixed with parity bits to the extension layer symbol extractor 650.

The extension layer symbol extractor 650 receives all bits from theenhanced layer error correction decoder of the enhanced layer BICMdecoder 540, and extracts extension layer symbols from the output signalof the de-injection level controller 1020.

In this case, the de-injection level controller 1020 may amplify thepower of the output signal of the subtracter of the enhanced layersymbol extractor 530.

In this case, the extension layer symbol extractor 650 includes abuffer, a subtracter, an enhanced layer symbol mapper, and an enhancedlayer bit interleaver. The buffer stores the output signal of thede-injection level controller 1020. The enhanced layer bit interleaverreceives the all bits information (bits+parity bits) of the enhancedlayer BICM decoder, and performs enhanced layer bit interleaving that isthe same as that of the transmitter. The enhanced layer symbol mappergenerates enhanced layer symbols, which are the same as those of thetransmitter, from the interleaved signal. The subtracter obtainsextension layer symbols by subtracting the output signal of the enhancedlayer symbol mapper from the signal stored in the buffer, and transfersthe extension layer symbols to the extension layer BICM decoder 660.

In this case, the enhanced layer bit interleaver and the enhanced layersymbol mapper included in the extension layer symbol extractor 650 maybe the same as the enhanced layer bit interleaver and the enhanced layersymbol mapper shown in FIG. 7 .

The de-injection level controller 1150 increases power by a level bywhich the injection level controller of a corresponding layer hasdecreased the power at the transmitter.

In this case, the de-injection level controller may be viewed asperforming the operation of multiplying the extension layer gain ofEquation 7 below. In this case, a 0-th injection level may be consideredto be 0 dB:

$\begin{matrix}{n‐{{{th}{extension}{layer}{gain}} = \frac{10^{‐{{Injectionlevel}\#{({n - 1})}{{({dB})}/10}}}}{10^{‐{{Injectionlevel}{\# n}{{({dB})}/10}}}}}} & (7)\end{matrix}$

The extension layer BICM decoder 660 receives the extension layersymbols whose power has been increased by the de-injection levelcontroller 1150, and restores extension layer data.

In this case, the extension layer BICM decoder 660 may include anextension layer symbol demapper, an extension layer bit deinterleaver,and an extension layer error correction decoder. The extension layersymbol demapper calculates LLR values related to the extension layersymbols, the extension layer bit deinterleaver strongly mixes thecalculated LLR values with burst errors, and the extension layer errorcorrection decoder corrects error occurring over a channel.

In particular, each of the extension layer symbol extractor and theextension layer BICM decoder may include two or more extractors ordecoders if two or more extension layers are present.

That is, in the example shown in FIG. 12 , the extension layer errorcorrection decoder of the extension layer BICM decoder 660 may outputonly information bits, and may output all bits in which information bitshave been combined with parity bits. In this case, the extension layererror correction decoder outputs only information bits as extensionlayer data, and may output all bits in which information bits have beenmixed with parity bits to the subsequent extension layer symbolextractor 670.

The configuration and operation of the extension layer symbol extractor670, the extension layer BICM decoder 680 and the de-injection levelcontroller 1170 can be easily understood from the configuration andoperation of the above-described extension layer symbol extractor 650,extension layer BICM decoder 660 and de-injection level controller 1150.

A lower one of the de-injection level controllers 1020, 1150 and 1170shown in FIG. 12 may correspond to a larger increase in power. That is,the de-injection level controller 1150 may increase power more than thede-injection level controller 1020, and the de-injection levelcontroller 1170 may increase power more than the de-injection levelcontroller 1150.

It can be seen that the signal demultiplexer shown in FIG. 12 restorescore layer data first, restores enhanced layer data using thecancellation of core layer symbols, and restores extension layer datausing the cancellation of enhanced layer symbols. Two or more extensionlayers may be provided, in which case restoration starts with anextension layer combined at a higher power level.

FIG. 13 is a diagram showing in an increase in power attributable to thecombination of a core layer signal and an enhanced layer signal.

Referring to FIG. 13 , it can be seen that when a multiplexed signal isgenerated by combining a core layer signal with an enhanced layer signalwhose power has been reduced by an injection level, the power level ofthe multiplexed signal is higher than the power level of the core layersignal or the enhanced layer signal.

In this case, the injection level that is adjusted by the injectionlevel controllers shown in FIGS. 3 and 7 may be adjusted from 3.0 dB to10.0 dB in steps of 0.5 dB. When the injection level is 3.0 dB, thepower of the enhanced layer signal is lower than that of the core layersignal by 3 dB. When the injection level is 10.0 dB, the power of theenhanced layer signal is lower than that of the core layer signal by 10dB. This relationship may be applied not only between a core layersignal and an enhanced layer signal but also between an enhanced layersignal and an extension layer signal or between extension layer signals.

The power normalizers shown in FIGS. 3 and 7 may adjust the power levelafter the combination, thereby solving problems, such as the distortionof the signal, that may be caused by an increase in power attributableto the combination.

FIG. 14 is an operation flowchart showing a method of generatingbroadcast signal frame according to an embodiment of the presentinvention.

Referring to FIG. 14 , in the method according to the embodiment of thepresent invention, BICM is applied to core layer data at step S1210.

Furthermore, in the method according to the embodiment of the presentinvention, BICM is applied to enhanced layer data at step S1220.

The BICM applied at step S1220 may be different from the BICM applied tostep S1210. In this case, the BICM applied at step S1220 may be lessrobust than the BICM applied to step S1210. In this case, the bit rateof the BICM applied at step S1220 may be less robust than that of theBICM applied to step S1210.

In this case, an enhanced layer signal may correspond to the enhancedlayer data that is restored based on cancellation corresponding to therestoration of the core layer data corresponding to a core layer signal.

Furthermore, in the method according to the embodiment of the presentinvention, a power-reduced enhanced layer signal is generated byreducing the power of the enhanced layer signal at step S1230.

In this case, at step S1230, an injection level may be changed from 3.0dB to 10.0 dB in steps of 0.5 dB.

Furthermore, in the method according to the embodiment of the presentinvention, a multiplexed signal is generated by combining the core layersignal and the power-reduced enhanced layer signal at step S1240.

That is, at step S1240, the core layer signal and the enhanced layersignal are combined at different power levels so that the power level ofthe enhanced layer signal is lower than the power level of the corelayer signal.

In this case, at step S1240, one or more extension layer signals havinglower power levels than the core layer signal and the enhanced layersignal may be combined with the core layer signal and the enhanced layersignal.

Furthermore, in the method according to the embodiment of the presentinvention, the power of the multiplexed signal is reduced at step S1250.

In this case, at step S1250, the power of the multiplexed signal may bereduced to the power of the core layer signal. In this case, at stepS1250, the power of the multiplexed signal may be reduced by a level bywhich the power has been increased at step S1240.

Furthermore, in the method according to the embodiment of the presentinvention, a time-interleaved signal is generated by performing timeinterleaving that is applied to both the core layer signal and theenhanced layer signal is performed at step S1260.

Furthermore, in the method according to the embodiment of the presentinvention, a broadcast signal frame including a bootstrap and a preambleis generated using the time-interleaved signal at step S1270.

In this case, the step S1270 may include generating the bootstrap;generating the preamble; and generating a super-imposed payloadcorresponding to the time-interleaved signal.

In this case, the bootstrap may be shorter than the preamble, and have afixed-length.

In this case, the bootstrap may include a symbol representing astructure of the preamble, the symbol corresponding to a fixed-lengthbit string representing a combination of a modulation scheme/code rate,a FFT size, a guard interval length and a pilot pattern of the preamble.

In this case, the symbol may correspond to a lookup table in which apreamble structure corresponding to a second FFT size is allocated priorto a preamble structure corresponding to a first FFT size, the secondFFT size being less than the first FFT size when the modulationscheme/code rates are the same, and a preamble structure correspondingto a second guard interval length is allocated prior to a preamblestructure corresponding to a first guard interval length, the secondguard interval length being longer than the first guard interval lengthwhen the modulation scheme/code rates are the same and the FFT sizes arethe same.

In this case, the broadcast signal frame may be an ATSC 3.0 frame.

In this case, the L1 signaling information may include injection levelinformation and/or normalizing factor information.

Although not explicitly shown in FIG. 14 , the method may furtherinclude the step of generating signaling information including injectionlevel information corresponding to step S1230. In this case, thesignaling information may be L1 signaling information.

The method of generating broadcast signal frame shown in FIG. 14 maycorrespond to step S210 shown in FIG. 2 .

As described above, the apparatus and method for generating broadcastsignal frame according to the present invention are not limited to theconfigurations and methods of the aforementioned embodiments, but someor all of the embodiments may be selectively combined such that theembodiments are modified in various manners.

1. A method of generating a broadcast signal frame, comprising:generating a power-reduced enhanced layer signal by reducing power of anenhanced layer signal; generating a multiplexed signal by combining acore layer signal and the power-reduced enhanced layer signal;generating a power-reduced multiplexed signal by reducing power of themultiplexed signal; generating a time-interleaved signal by performingtime interleaving that is applied to both a core layer corresponding tothe core layer signal and an enhanced layer corresponding to theenhanced layer signal; and generating a broadcast signal frame includinga bootstrap and a preamble using the time-interleaved signal, whereinthe bootstrap is located at the beginning of the broadcast signal frameand includes a symbol representing a structure of the preamble, andwherein the preamble is located immediately following the bootstrap. 2.The method of claim 1, wherein the symbol corresponding to afixed-length bit string representing a combination of a Layer-1(L1)-Basic Mode, a Fast Fourier Transform size, a guard interval lengthand a pilot pattern of the preamble, and the power-reduced multiplexedsignal is generated corresponding to a normalizing factor which isapplied to both the core layer signal and the power-reduced enhancedlayer signal.
 3. The method of claim 2, wherein the broadcast signalframe includes the bootstrap; the preamble; and a payload correspondingto the time-interleaved signal.
 4. The method of claim 2, wherein thesymbol corresponds to a lookup table in which a preamble structurecorresponding to a second Fast Fourier Transform size is allocated priorto a preamble structure corresponding to a first Fast Fourier Transformsize, the second Fast Fourier Transform size being less than the firstFast Fourier Transform size when the Layer-1 (L1)-Basic Modes are thesame.